1. Field of the Invention
The present invention relates to a liquid-sealed vibration-proof device, for example, for an automobile, to be built in a support mechanism for a differential, engine, etc., or a part of a suspension mechanism in order to damp vibrations transmitted to the vehicle body.
2. Description of the Related Art
In an automobile, a liquid-sealed vibration-proof device may be, in general, built in a support mechanism for a differential or engine or a part of a suspension mechanism with the aim of damping vibrations transmitted to the vehicle body. One example of such a liquid-sealed vibration-proof device is illustrated in FIGS. 18-21. FIG. 18 is a perspective view of the liquid-sealed vibration-proof device showing its state before an outer cylinder is fitted.
This liquid-sealed type of vibration-proof device is provided with an inner cylinder 101 made of steel, an outer cylinder 102 made of aluminum arranged outwardly to and in a spaced relation to the inner cylinder 101, and an antivibratory base 103 made of rubber-like elastomer interposed between the inner and outer cylinders 101, 102. The inner cylinder 101 is mounted on a differential case and the outer cylinder 102 is mounted on the side of the vehicle body, whereby both are connected in a vibration-proof manner.
At an outer circumferential side of the antivibratory base 103, there is secured an intermediate cylinder 104 of steel interposed between the outer cylinder 102 and the antivibratory base 103. This intermediate cylinder 104 includes intermediate rings 105 secured to the antivibratory base 103 in the vicinity of both axial ends thereof and a connecting element 106 connecting both intermediate rings 105 in its axial direction, with the intermediate rings 105 being secured to an inner peripheral surface of the outer cylinder 102, to which the antivibratory base 103 is secured.
On an outer circumferential surface of the intermediate ring 105, two pieces of projecting streaks 107 made of rubber-like elastomer are formed to seal between the outer cylinder 102 and the intermediate ring 105 and concurrently to prevent the contact between the outer cylinder 102 and the intermediate ring 105 thereby precluding corrosion due to any electric potential difference when the different metals contact each other.
Between both intermediate rings 105 at the outer circumferential side of the antivibratory base 103, there are two spaces 109 divided by a partition wall 108. By reducing the diameter of the outer cylinder 102 within a liquid tank and then fixing it to the intermediate rings 105, the spaces 109 are enclosed by the outer cylinder 102 and two liquid chambers 111 communicating with each other through an orifice 110 are thus constructed.
FIG. 19 is an enlarged sectional view of the outer cylinder prior to its diameter reduction in the vicinity of the intermediate ring, FIG. 20 is an enlarged sectional view of the outer cylinder after the diameter reduction in the vicinity of the intermediate ring and FIG. 21 is an enlarged sectional view of the outer cylinder when press fitted in an opening on the vehicle body in the vicinity of the intermediate ring. When the outer cylinder 102 is reduced in diameter within the liquid tank and its inner peripheral surface contacts both the projecting streaks 107, a space enclosed by the outer cylinder 102, the intermediate rings 105 and the projecting streaks 107 is shut off from outside. A liquid 113 in the space 112 still remains there after the diameter of the outer cylinder 102 has been reduced.
Since the outer cylinder 102 press fitted in the opening of the body side member has a reduced diameter when the liquid-sealed vibration-proof device is installed to the vehicle body side, the volume of the space 112 in which the liquid 113 is sealed is decreased. Therefore, there is a danger of part of the liquid 113 leaking between the projecting streak 107 located on the opposite side to the liquid chamber 111 and the outer cylinder 102.
It is an object of this invention to provide a liquid-sealed vibration-proof device capable of preventing leakage of the liquid in press fitting and fixing its outer cylinder into the opening of an attachment member.
In order to achieve this object, this invention provides a liquid-sealed vibration-proof device comprising an inner cylinder, an outer cylinder spaced apart outwardly from the inner cylinder, an intermediate ring interposed between an outer circumferential side of the inner cylinder and an outer circumferential side of the outer cylinder, wherein a space formed on the outer circumferential side of the antivibratory base at an axially central side from the intermediate ring is enclosed by the outer cylinder to thereby constitute a liquid chamber. In the device, the outer cylinder and the intermediate ring are made of different metals, and two projecting streaks of rubber-like elastomer are formed on an outer circumferential surface of the intermediate ring, with one projecting streak on the liquid chamber side being formed with cutouts.
The invention is thus a liquid-sealed vibration-proof device in which the intermediate ring is interposed between the outer circumferential side of the antivibratory base and the inner circumferential side of the outer cylinder so that the outer cylinder and the antivibratory base may be fixed by diameter reduction of the outer cylinder and press fitting, etc. of the antivibratory base into the outer cylinder. Two projecting streaks of rubber-like elastomer are formed on the outer circumferential surface of the intermediate ring to prevent leakage of liquid out of the liquid chamber and contact between the outer cylinder and intermediate ring which are made of different metals. In the device in accordance with this embodiment of the invention, the projecting streak on the liquid chamber side is formed with cutouts.
In the liquid-sealed vibration-proof device in accordance with the invention, when press fitted and fixed in the opening of an attachment member, the outer cylinder is reduced in diameter whereby the liquid confined in the space enclosed by the outer cylinder, the intermediate ring and both projecting streaks is drained out of the space. By forming the cutouts at the projecting streak on the liquid chamber side, it is possible to direct the confined liquid to the liquid chamber side so that the liquid may not leak outside.
The fixing part of the outer cylinder and the antivibratory base is not always required to be interposed by the intermediate ring in the entirety thereof. Of both axially terminal sides of the liquid chamber, the intermediate ring may be interposed at the one side to fix the outer cylinder and the antivibratory base whereas the outer cylinder and the antivibratory base may be directly bonded together at the other side. In that case, for example, while compressing the antivibratory base at its direct bonding side to the outer cylinder, the outer cylinder is reduced in diameter in the liquid tank. Otherwise, the antivibratory base is formed so that the intermediate ring may be located axially outside the outer cylinder and then, in the liquid tank, the intermediate ring is axially forced and press fitted into the outer cylinder while deforming the antivibratory base, whereby the liquid chamber is sealed with the liquid.
Further, in the liquid-sealed vibration-proof device in accordance with the invention, the intermediate rings may be secured to the outer circumferential side of the antivibratory base each at a respective one of the axial sides of the liquid chamber, and both intermediate rings at both axial sides are connected through the connecting element thereby forming an intermediate cylinder interposed between the antivibratory base and the outer cylinder.
In other words, according to the invention, the intermediate rings axially connected through the connecting element are secured at both axial sides of the liquid chamber to the outer circumferential side of the antivibratory base. Consequently, it is possible to mold the antivibratory base without the outer cylinder and the molding can be simplified. It is also possible to make the distance between both axially sides of the liquid chamber definite to thereby make the volume of the liquid chamber a predetermined size.
Furthermore, in the liquid-sealed vibration-proof device in accordance with the invention the outer cylinder may be made of aluminum and the intermediate ring may be made of steel, which provides a preferred embodiment of the liquid-sealed vibration-proof device in accordance with the invention.
Thus, when the vehicle body member is made of aluminum to render the weight of the vehicle body lighter, the outer cylinder can be made of aluminum, whereby it is possible to avoid the corrosion resulting from any electric potential difference between the outer cylinder and the member on the body side. On the other hand, the intermediate ring can be made of steel thus making its dimensions smaller, whereby the size of the device is reduced.